Chair

$\begin{figure}\begin{center}\BoxedEPSF{Chair.epsf}\end{center}\end{figure}$

A Surface with tetrahedral symmetry which, according to Nordstrand, looks like an inflatable chair from the 1970s. It is given by the implicit equation

$\begin{displaymath} (x^2+y^2+z^2-ak^2)^2-b[(z-k)^2-2x^2][(z+k)^2-2y^2]=0. \end{displaymath}$

See also Bride's Chair

References

Nordstrand, T. ``Chair.'' http://www.uib.no/people/nfytn/chairtxt.htm.